one direction

i am using 2 Xbee 900 pro units. One is plugged into a sparkfun usb adaptor baord and is driven by the configuration softare. If I put this unit into range test mode I get an ascii stream transmitted in bursts to the remote unit.

The remote unit is connected to an Mbed embedded board which is acting as a simple usb/serial converter.

Although transmission from PC to mbed is faultless, all charachters received no dropouts etc, trying to send a charachter back from the mbed to the PC is useless.

Transmitting a single ā€˜Uā€™ charachter gets as far as the Xbee ( and a scope confirms this ) The xbee instantly reflects a charachter, nothing like what I sent, its a garbage character in the high Fx range ( FC,FD FE FF ) and nothing appears at the pc side of the link.

This appears to be similar to one or two other thread in the forum but non of which have a solution attached.